Rhythmogenesis in vasopressin cells.

Many neurones in the central nervous system possess intrinsic pattern-generating properties, including vasopressin magnocellular neurosecretory cells. Synaptic input to vasopressin cells is not rhythmically patterned and yet these neurones fire action potentials in a 'phasic' activity pattern comprised of alternating periods of activity and silence that each last tens of seconds. This review describes the intrinsic and extrinsic mechanisms that generate phasic activity in vasopressin cells, highlighting recent work that has shown phasic activity to result from feedback modulation of synaptic inputs, and of intrinsic membrane properties, by peptides released from the dendrites of vasopressin cells.